K-Patents PR-01-S - Manual (Page 21)

INSTRUCTION MANUAL FOR K-PATENTS PR-01-S (-AX/FM/CS) DOCUMENT/REVISION No. INM 1/14
Effective: May 15, 2009
19
3. MOUNTING
Special precautions have to be taken when an intrinsically safe system is mounted, see Section 12.2.
3.1. SENSOR LOCATION
The sensor is delivered with a mounting guide attached, Figure 3.10.
The sensor is designed for being installed directly in a process line. If the sensor is located out of doors,
some basic protection against direct exposure to sunlight and rain should be provided.
Air-cooling
Normally, draught and natural convection provide sufficient air cooling. Criteria for efficient air-cooling:
1. The sensor should be mounted with the main axis horizontal, Figure 3.10.
2. There must be no obstacles for air to flow around the sensor head.
3. The red sensor cover should not be exposed to high temperature radiation.
If the ambient temperature is higher than 45°C (113°F) the air-cooling should be improved by blowing
pressurized air against the red sensor cover. This is also recommended when the process temperature is
above 110°C (230°F) when the ambient temperature is above 35°C (95°F).
The pressurized air can be supplied by the ventilation system. If no air is available it is possible to wind a
copper coil for cooling water around the sensor head cover.
Process flow conditions
The sensor is designed to make the prism self-cleaning. To ensure a representative sample and also prism
cleaning action, a good process flow should be directed against the prism surface. A flow velocity above
1.5 m/s (5 ft/s) is recommended. For lower velocities prism wash (Chapter 8) should be considered. Flow
velocity is calculated from v[m/s] = 21.2 * Flow[lit/min]/d²[mm]; v[m/s] = 0.125 * Flow[Gpm]/d²[in].
Accumulation of sediment or of gas bubbles should be prevented.
If the process pipe vibrates, support the pipe.